And thomas



(No Model.) 7

M. D. 80 T. A. CONNOLLY.

PROTECTOR FOR ELECTRICAL INSTRUMENTS. N0. 279;?13. Patented June 19,1883.

KN KN .ZQJZL WITNESSES v I fINVENTOR S 1 fl&.

ATTORNEYS 5 arranged in the ordinary way Umrnn STATES ATENT OFFICE.

31.. DANIEL OONNOLLY, OF PHILADELPHIA, PENNSYLVANIA, AND THOMAS A. CONNOLLY, OF WASHINGTON, DISTRICT OF COLUMBIA.

PROTECTOR FOR ELZECTRICAL \NSTRUMENTS.

SPECIFICATION forming part of Letters Patent No. 279,713, dated June 19, 1883.

Application filed February 16, 1883.

To all whom it may concern:

Be it known that we, M. DANIEL OoNNoLLY, a citizen of the United States, residing at Philadelphia, in. the county of Philadelphia and State of Pennsylvania, and THOMAS A. CON- NOLLY, a citizen of the United States, residing at \Vashington, in the District of Oolum bia, have invented certain new and useful Im' provcments in Protectors for Electrical I11- struments; and we do hereby declare the following to be a full, clear, and exact description of the invention, reference being had to the accompanying drawing, which forms part of this specification, in which is shown a side I 5 elevation ofa telephonic exchange annunciatormagnet with protecting devices.

Our invention has relation to that class of devices known as protectors for telegraphic, telephonic, and other electrical instruments,

and which operate, when abnormallypowerful currents fall on the line, to divert the same to ground or return by change of circuit through the movement of an armature.

Our improvements have for their object to 2 5 provide a construction of suchprotector which will avoid needless duplication of parts at telephonic exchanges and other places where en tering electric wires lead to an annunciator.

Our improvements consist in so constructing such annunciators that while they will perform their usualservices when actuated by ordinary working-currents they will also operate as protectors against the injurious effects of abnormally-powerful currents accidental '3 5 circuiting through the lines.

Our improvements consist accordingly, in the first place, in constructing an annunciator so that it will operate as a protector; and, secondly, in the specific construction and combi- 0 nation of parts hereinafter described.

Referring to the accompanying drawing, A indicates a portion of the annunciator of a telephone-exchange or like office. I

B designates the shutter or drop, which is to be held up by a catch on the armature-lever B, and allowed to fall when the armature is attracted toward the annunciator-magnet O. The line enters the magnet O and continues thence to the telephone or other device located in its path to earth or return, as maybe convenient (N0 modem or usual, for signaling or calling purposes.

verting the same to earth.

The ordinary working-circuit is in the direction described. From the line outside the magnet a branch, a, leads to a stop or conducting-point, D, attached to the magnet-head or to any other suitable insulated support. Another branch line, f, leads from the arma ture-lever to ground. The armature-lever is provided with a stop, 9, or has its under side '60- suitably adapted to make contact with the stop D when the armature is brought in contact with the pole or poles of the magnet. Such contact of armature or pole can only take place when the magnet is strongly energized 6 5 by a powerful abnormal current, its movement under ordinary circumstances being limited by a spring catch, G, against which presses the elongated point h of the armature lever. Sufficient play is, however, allowed to effect a release of the annunciator-drop- A powerful current attracts the armature with sufficient force to overcome the obstruction of the spring-catch and bring the stops D g in contact.- At the same time an engagement is 7 5 effected between said catch and the armaturelever, and the latter is held down. As soon as the stops D 9 come together a new path is formed for the current, being then through the branch (I, armature-lever B, and earth '80 branch f, which path the current takes by preference, as it is of practically no resistance, being outside and independent of the magnet. The magnet is therefore protected, as are also the telephone, bell, and other instruments, from 8 5 burning or other injury, .as the initial stroke or passage of the current is but momentary, the annunciator-magnet responding instantly to the powerful current, and immediately di- Each of theannunciator-magnets should be provided with the parts and circuits suggested, whereby the provision of special protectingmagnets and appurtenances is avoided, each annunciatormagnet being practically a selfacting protector for itself and for the other instrument on the line to which it pertains.

\Vhat we claim as our invention is- 1. The combination, with a magnet and its armature-lever, constructed and adapted for annunciator purposes, of the spring-catch G, contacts D g, and connections a f, whereby change of circuit is effected and maintained the establishment of the shunt-circuit,and the when said magnet is powerfully or abnormally engagement of the eateh with the lever, subenergized, substantially as described. stantially as described.

2. The combination, with an aununeiator- In testimony that we claim the loi'egoing we magnet, itsarmature, armatuire-lever, and drop have hereunto set our hands or shutter, said armature-lever being con- Febrnary, 1883. strueted and adapted to retain said drop and M. DANL CONNOLLY. to release it when the magnet is energized by THOMAS A CONNOT T Y normal currents, of suitable contacts, shunts, J J and a catch, whereby abnormal currents will lVitnesses:

A. A. CoNNoLLY, l). M oinm'm.

be shorteireiiited to earth, and the short eireuit maintained by the closing ol'said contact s,

this 14th day of 

